Causes and evolution of group‐living

Sociality, or group-living, results when conspecifics establish long-term (relative to lifespan) and spatially cohesive social units. Sociality theory states that group-living evolves whenever individuals attain net fitness benefits, or when individuals are forced to remain in groups. Among rodents, this theory comes from the study of a relatively small sample of taxonomic groups, typically from African mole-rats and North American squirrels and marmots. We reviewed published studies and data on the sociality of caviomorph rodents and argue that these rodents are particularly informative when refining a sociality theory. Our examination of evidence from caviomorphs indicated that resource heterogeneity (food, water pools) may act either as a constraint or a condition that promotes social benefits, depending on species. Instead, a benefit based on enhanced vigilance seems relatively common across species. Other predation benefits may have been overlooked. Benefits based on social thermoregulation or energetic savings during cooperative burrow construction come from the study of a few species and are restricted to laboratory settings. Evolutionary studies based on comparative approaches highlight that both ecological and life history traits have influenced sociality in caviomorphs. Besides, sociality was likely an ancestral condition across these rodents, implying that sociality in some extant species may be the legacy of social ancestors. Future research should determine multi-dimensional causes of social variation and intra-specific variation in sociality in well-studied taxa and examine the relationship between sociality, life-history, and ecology across taxa.